Comparison of some Stylosanthes species in the dry tropics of Queensland

Abstract

Fifteen accessions, comprising Stylosanthes guyanensis (1 ), ., hamata (5), S. humilis (2), S. subsericea (5) and interspecific hybrids (2), were compared when grown in swards with the grass Urochloa mosambicensis at three sites in the dry tropics of Queensland with an average growing season ranging from 11.5 to 22.0 weeks per annum. The swards were harvested at 6-weekly intervals during the growing season at a height of 7.6 cm. Over the three years of the trial, S. hamata CPI 38842 (cv. Verano) was superior in dry matter yield over all sites to the other accessions, including the two S. humilis cultivars cv. Paterson and cv. Lawson. Nodulation problems prevented an adequate comparison of four other S, hamata accessions except at 'Fanning River', where CPI 40264A and 40268 nodulated effectively and were as productive as cv. Verano. All S. hamata accessions perennated but gave lower pod yields and seedling regeneration than S. humilis cultivars. In vitro digestibility of the S. hamata accessions was lower than S. humilis in May but higher in September. Although S. subsericea accessions nodulated readily at all sites, their performance was site-sensitive and all but one accession failed to perennate.